Figure 1
From: An algorithm for automatic evaluation of the spot quality in two-color DNA microarray experiments
Example of a spot with a low DW parameter (0.45). Although the coefficient of determination of the linear regression plot (red line) is relatively high (0.92), it is obvious that the linear regression model is not appropriate in this case. It is possible that there are contributions (blue lines) from two different species occurring within the given spot, leading to two different Cy5/Cy3 ratios. The background pixels are grouped near the origin of the linear regression plot (cyan circle).